Nice info thanks. This seems though, to pertain to lead-in and lead-out lighting/marking as per FAA rules. Even without lighting involved, lead-in / lead-out marking is mandatory as per FAA circular 4.2.b.(2)
https://www.faasafety.gov/files/gsla...1K_change1.pdf
However according to ICAO, there exists a requirement to have a lead-out line when a taxiway is meant as an exit - there is no mention of a lead-in.
Ref 5.2.8.7 Visual aids for navigation annex 14, it recommends a curved lead-out line when a taxiway serves as an exit to a runway
http://www.orga.nl/pdf/Chapter%205%2...Navigation.pdf
I guess one can use a lead out line as a lead-in when one exists, as long as regard line up requirements for the runway in question, are met. Most airlines these days lay out their own line up techniques with runway length loss built into their OPTs and outlined in their Ops manuals.
Cheers